Single-phase (Hf-Mo-Nb-Ta-Ti)C high-entropy ceramic: A potential high temperature anti-wear material

The single-phase (Hf0.2Mo0.2Nb0.2Ta0.2Ti0.2)C ceramics with uniform composition have been prepared by spark plasma sintering. The microstructure, mechanical and tribological properties were studied. The experimental results indicate that grain size and densification degree determine their mechanical properties. Meanwhile, the high temperature deteriorates their hardness and fracture toughness. The HEC3 sintered at 2000 °C exhibits excellent mechanical properties and wear resistance. Its hardness and fracture toughness are 18.5 GPa and 4.2 MPam1/2 at 25 °C, respectively. And its wear rate is as low as 10−5-10−7 mm3/Nm at 25–600 °C. The outstanding wear resistance benefits from the synergistic effect of the generated tribo-film and excellent mechanical properties. This material is expected to be a novel kind of high-temperature materials for tribological application.